That would be my own first science fiction novel, Ptolia, Book One. Written in 1975, it was finally published in 1982 and sold something like 8,000 or 9,000 copies right out of the gate...but that was it. Reviews by readers were highly favorable, but there just weren't enough of them, and the publisher's promotions only reached a very small niche group of people.
My favorite review was by a 15 year old boy. I worked in the oil patch as a workover rig derrick hand when the book was released. The 15 year old was my Supervisor's son. He (a) read it, (b) wrote a book report on it for school, and (c) in that report stated that, "...it would make a great video game!"
Can't get much higher praise from that from a high school sophomore.
My style has evolved exponentially since then, but it was fine for a first novel.
I just checked Amazon. Looks like 18 copies available there (from just about that many sellers).